Electronic mail (Email) has become ubiquitous. Email is used to transmit messages over communications networks. The messages can be notes entered from a keyboard or electronic files stored on a disk. Most Email systems have gateways to other computer systems, enabling users to send Email virtually anywhere in the world. Email has proven to be a fast, flexible, and reliable means of communication. Once a message is composed, the message is sent to the recipient by specifying the recipient's address. Sent messages are stored in electronic mailboxes until the recipient fetches them. To see if a user has any Email, the user checks their electronic mailbox, although many systems alert a user when an Email is received. After reading an Email, the user can store the Email message in a text file, forward the Email message to other users, or delete the message. Most online services and Internet Service Providers (ISPs) offer e-mail, and most also support gateways so that Email can be exchanged with users of other systems. Email has proven to be a particularly effective way to communicate with a group because messages can be broadcast to everyone in a group at once.
Instant Messaging (IM), is a type of communications service that enables a user to create a kind of private chat room with another individual in order to communicate in real time over the Internet, analogous to a telephone conversation but using text-based, not voice-based, communication. Typically, the IM system alerts the user whenever somebody on the user's private list is online. The user can then initiate a chat session with that particular individual.
IM requires the use of a client program that hooks up an instant messaging service and differs from e-mail in that conversations are then able to happen in real-time. Most IM services offer a presence information feature, indicating whether people on one's list of contacts are currently online and are available to chat. Most instant messaging applications also include the ability to set a status message, roughly analogous to the message on a telephone answering machine.
Instant messaging typically boosts communication and allows easy collaboration. In contrast to e-mails or phone, the parties know whether the peer is available. Most IM systems allow the user to set an online status or away message so peers get notified whenever the user is available, busy, or away from the computer. People are not forced to reply immediately to incoming messages. This way, communication via IM can be less intrusive than communication via phone, which is partly a reason why IM is becoming more and more important in corporate environments. Instant messages typically get logged in a local message history, facilitating quick, safe, and persistent exchange of information such as URLs or document snippets, which can be unwieldy when done using inappropriate media such as a phone.